Modern helical CT technology, coupled with a rapid tntravenous infusion of iodinated contrast media, allows for the creation of volumetric angiograms. To date, volumetric angiograms have been visualized qualitatively with various three-dimensional rendering techniques, but a systematic, quantitative analysis of blood vessel morphology has not been conducted. Our goal is to develop and validate a method of volumetric analysis that enables quantification of cross-sectional areas of blood vessels, path lengths, curvature and branch angulation, as well as mural plaque/thrombus characteristics such as volume, calcification and irregularity. We will validate these measurements in idealized and anthropomorphic phantoms, and then apply the volumetric analysis to the problem of characterizing the aorta and its branches for the purpose of endovascular repair of aortic aneurysms with stent-grafts. In the clinical application phase of our work, we will test the hypothesis that volumetric analysis of helical CT angiograms improves planning for endovascular prosthesis deployment, leads to a lower proportion of adverse outcomes, and may obviate the need for invasive arteriography from pre-deployment evaluation.